Commercial refrigerators and refrigerated display cases (coolers and freezers) are used in markets, food-vending operations, liquor stores for the preservation of freshness and attractive display of product to the customer. Typically, commercial display cases have frames defining a rectangular opening for the case which is accessed through sliding doors or swing doors having large areas of multi-layered glazing to permit the customer to see, select and access the refrigerated product easily, while preventing heat transfer into the refrigerated space. The display case frame includes an upper frame member, a lower frame member, two laterally spaced side frame members extending vertically between the upper and the lower frame members, and one or more mullions which extend vertically between the upper frame member and the lower frame member and connected thereto. The mullion provides support for the cabinet frame, associated doors, and also provides a sealing surface against which portions of the door assemblies engage and seal for effective sealing of the refrigerated cabinet. Typically, mullions are also equipped with electrical conduits for delivering electrical power to anti-condensation devices for the door assemblies and for a fluorescent lighting fixture associated with the mullion.
Conventional refrigerated display cases typically include a fluorescent light source to illuminate the product display area. Some refrigerated display cases include fluorescent light sources coupled to a canopy of the refrigerated display cases to direct light generally downward onto the food product in the product display area. These refrigerated display cases also may include fluorescent light sources attached to shelves in the product display area. Generally, the fluorescent light sources used in conventional refrigerated merchandisers are relatively large, and can reduce the amount of space in the refrigerated merchandiser that can be allocated to displaying food product. Fluorescent light sources also generate heat which causes the refrigeration unit to work harder and consume more energy.
Furthermore, the effectiveness of fluorescent light sources is dependent on the temperature of the application where the fluorescent light sources are used. In colder temperature conditions, the fluorescent light source has less light output than in application of the fluorescent light source in warmer temperature conditions. As a result, fluorescent light sources within the refrigerated display cases have substantially reduced effective illumination of the products within the product display area. Additionally, at lower operating temperatures initiating the required arc to illuminate a fluorescent tube is difficult.
Known lighting assemblies often also suffer from a number of problems when it comes to lighting display cases including issues pertaining to efficiency, lighting uniformity, consumer appeal, customization, and maintenance. Lighting assemblies often allow light to escape the display case and bleed out into the external environment. However, this escaping light could be put to better use lighting the item(s) on display, whereby less powerful and/or or fewer light sources could be employed. Further, lighting assemblies generally do not uniformly light a display case. For example, such assemblies generally fail to direct enough light to the center of a display case, resulting in much higher luminance in front of a mullion, as compared to the center of the display case. However, uniform luminance is preferable as it makes more efficient use of the available luminance and may allow fewer light sources and/or less powerful light sources.
Recently, fluorescent light sources have begun to be phased out in favor light emitting diodes (LED) technology. Fluorescent tubes are relatively inefficient by comparison to LEDs, since fluorescent tubes produce more heat than LEDs and LEDs provide more control over the direction of light provided. Fluorescent tubes do not have nearly as long an operating life as typical LED.
Thus, there exists a need for modular track LED lighting that provides for improved product lighting in display cases, including refrigeration applications.